In a large saucepan, bring 2 quarts / 1. 9 L of water to a rolling boil.
Remove from the heat, add the tea bags, and let steep for 20 minutes. 2. Carefully remove the tea bags, gently squeezing out the excess liquid before discarding.
Stir the erythritol and liquid stevia into the hot tea until fully dissolved. 3.
Pour the remaining 2 quarts / 1. 9 L of cold water into a gallon-sized pitcher.
Add the sweetened tea concentrate and stir thoroughly to combine. 4.
Serve chilled over ice in tall glasses, garnished with lemon wedges. Store in a covered pitcher in the refrigerator for up to 1 week.
Don't over-steep. Steeping black tea for much longer than 20 minutes can release excess tannins, resulting in a bitter-tasting tea.